There is currently little documentation for QPA. The best approach for developing a new platform plugin is to look at the other plugins[qt.gitorious.net] and see how they implement the APIs in question. The minimal[qt.gitorious.net] plugin is a good starting point. The xcb, windows, cocoa, and qnx plugins are also actively developed and up to date.

QPA plugins are implemented by subclassing various QPlatform* classes. There are two “root” classes: QPlatformIntegration for window system integration and QPlatformTheme for deeper platform theming and integration. QStyle is not a part of QPA.

The APIs provided by QPlatformIntegration are at this point (Qt 5 Alpha) mostly stable. QPlatformTheme still has ongoing development. There
are no source or binary compatibility guarantees for the QPA classes, meaning that a platform plugin is only guaranteed to work with the Qt version it was developed against. API changes will however only be made in minor releases. (5.1, 5.2, and so on.)